This invention relates to optical broadcast network systems.
Local area networks (LANs) connect personal and mini-computers with each other and with other shared resources, for example, printers, file servers, and mainframe computers. Separate LANs can be joined via bridges to form larger linked systems of computers and shared resources.
Infrared communication techniques for LAN systems are attractive because they offer a number of benefits, including low transceiver costs, low power consumption, high device reliability, high biosafety, low installation costs, and little required cabling. Broadcast IR LAN networks allow computers and other LAN devices to connect to a LAN without cabling, providing easy mobility throughout an office or campus. However, since broadcast IR signal strength attenuates typically with the inverse square of distance from a transmitter, broadcast IR networks suffer from low signal strengths and corresponding high noise. To compensate, such LANs typically use a relatively large number of LAN transmitter sites (transmitters directly connected to a LAN cabled backbone). What is needed are apparatus and methods for easily and inexpensively extending the range of optical transceivers for LANs while ensuring relatively high signal-to-noise ratios.